1. Field of the Invention
The present invention relates to a blower fan of an inner-rotor type.
2. Description of the Related Art
In recent years, electronic devices, such as notebook personal computers and tablet personal computers, have been becoming thinner and thinner. In addition, such electronic devices have been becoming more and more sophisticated in functionality, causing a considerable increase in generation of heat in the electronic devices. Inside such slim electronic devices, a large number of electronic components are arranged, and a space occupied by an air is not large. Therefore, even in the case where components inside such an electronic device do not generate much heat, an increase in a temperature inside the electronic device may not be negligible. Accordingly, a blower fan is arranged in the electronic device with the view of cooling an interior of the electronic device.
In a slim electronic device, a centrifugal fan is arranged as a blower fan. The blower fan is required to have a certain air volume. Such blower fans are disclosed, for example, in JP-A 2013-130094 and JP-A 2001-241395. A centrifugal fan described in JP-A 2013-130094 is of an outer-rotor type. An electronic component arranging portion of a board is arranged in a region surrounded by a wide gap portion, an impeller, and an air outlet. A fan apparatus described in JP-A 2001-241395 is also of the outer-rotor type.
A blower fan of the outer-rotor type has a large rotating portion, and this makes it difficult to reduce the size of the blower fan of the outer-rotor type. Accordingly, a blower fan of an inner-rotor type may be adopted with the view of reducing the size of the blower fan. In this case, however, a large number of components of a motor portion are arranged to axially overlap with one another, and this makes it difficult to reduce the thickness of the blower fan of the inner-rotor type. As a result, it is difficult to secure a sufficient air volume while achieving a reduction in the thickness of the blower fan of the inner-rotor type.